A two step process is utilized in order to create a finished photograph from a negative. First, the image on the negative is projected onto a light sensitive medium. This portion of the procedure utilizes a printer. Subsequent to the light sensitive medium being exposed to the light projected from the negative, the medium is then processed in a known manner. This portion of the procedure utilizes a processor.
The printer apparatus typically includes a diffusion light head or a light mixing chamber which is used in connection with a white light source. The light is passed through the negative subsequent to the mixing chamber. A lens, or group of lenses then magnify the image from the negative onto a platen. The platen holds the light sensitive medium during the printing process.
For a more detailed description of a printer and a processor, reference may be had to commonly assigned application Ser. No. 07/278,668, titled Photographic Printer-Processor, which is hereby incorporated by reference.
While printers are known in the art, there are several drawbacks associated with their use. Several drawbacks include the types of mixing chambers available, the lens arrangements, and the light sensitive medium supply/take-up holding devices.
As noted, typically, mixing chambers are resident in printers between the light source and the negative. The light source is generally a white source (i.e., the source emits a full spectrum of colors so as to appear "white") and, if color printing, a number of color correction filters are provided between the light source and the negative. The color filters are provided in order to adjust the chromaticity as necessary to provide the desired color mix. As is well known in the art, the color correction filters are selectively moved into a portion of the light beam to adjust for color printing. A portion of the beam is thereby colored. It will be appreciated that the interposition of the color filter affects not only the color of that portion of the beam, but also the light flux through that portion. The mixing chamber is therefore interposed between the color filter (so as to accept the light) and the negative. The mixing chamber "scrambles" the light which enters the chamber and provides a homogeneous mix of light at the chamber's exit port. By homogeneous mixture, what is meant is both a uniform mixture of color and light flux.
Those skilled in the art will appreciate that it is desireable to minimize exposure times and that to do so requires a maximization of flux upon the negative. However, as negative sizes vary, the exit port of the mixing chamber will either be too small or too large relative to the negative. Therefore, only the largest negatives are uniformly illuminated and with a maximum degree of efficiency. For example, if the same size chamber is utilized with a large negative as a smaller negative, then a portion of the light is in essence blocked with an opaque mask when used with the smaller negative (i.e., the opaque mask is that portion of the negative mask/holder for the smaller negative). The loss of light results in a longer (relatively speaking) projection time.
In order to avoid such a result, typically, prior mixing chambers were made to be manually interchangeable so as to provide for variously sized exit ports which correspond to negative sizes. However, interchanging mixing chambers requires the interruption of the printing process and requires additional expense and storage.
U.S. Pat. No. 3,874,792 disclosed a two-sized mixing chamber by providing a pyramid shaped chamber, wherein a portion of each side wall hinged inwardly to form an interior rectangular chamber. Therefore, there was a first size corresponding to the base of the pyramid and a second size corresponding to the rectangular interior chamber. However, this device suffers from the drawback that it is inherently limited to two sizes. Therefore, there is a need for an adjustable mixing chamber which may be changed to correspond to variously sized negatives.
The second drawback of current printer devices is that many printers accommodate only a single lens so that the possible print sizes are limited. In printers which enable multiple lenses to be used, changing lenses can be a complicated process. The arrangement for holding the various lenses, such as a lens drawer system, can be quite complex and heavy and may require manual operation. Further, while lens "carousels" are known in the art, they typically include a single disk wherein the mean plane formed by the disk intersects the optical axis of each of the lenses held by the carousel. This arrangement necessarily limits both the number of lenses held by the carousel and the focal lengths of the lenses which might be used.
U.S. application No. 07/278,668, incorporated by reference above, discloses an arrangement of lenses which are both offset and staggered about a single axis of rotation. The lenses may be selectively rotated about the axis of rotation and into the light path. This provides for selecting lenses with differing focal lengths, but does not provide for a large group of lenses. Therefore, there is a need for an apparatus which provides for a large group of lenses and for lenses of differing focal lengths.
The third drawback of current printer devices is the lack of registration, or a solid reference point, for the edge of the supply web of light sensitive medium. Present printers typically utilize light sensitive paper which is in a web form, usually being provided in rolls of stock. However, while the web material has a nominal width, the variance allowed by the web material manufacturers oftentimes results in an undersized roll. Present printers do not accommodate for such variations. The result is a "serpentining" or wavering of the roll back and forth between the two ends of the supply roll holder. This may result in a similar serpentine result of the material as it passes over the platen during exposure. Therefore, there is a need for an apparatus which positively guides the web material and provides a solid reference despite a variance of nominal width.